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Jerry Clark
06-06-2007, 8:43 PM
This is interesting concept, but may not be feasible for transportation. :rolleyes:



http://www.digitaljournal.com/article/116641/Car_Runs_on_Compressed_Air

Pat Germain
06-06-2007, 8:54 PM
I've seen that before and it's a pretty clever concept. The idea of a vehicle running on compressed air isn't new. However, this guy seems to have made it at least somewhat practical.

You can make a car run on almost anything. Unfortunately, it's hard to beat gasoline. Almost nothing has as much energy per drop as gasoline. As gasoline becomes more expensive, perhaps the other fuels will become more practical.

As it stands now, alcohol fuels require twice as much fuel-to-air. Thus, running pure ethanol cuts your mileage literally in half.

Bill Lewis
06-07-2007, 2:08 PM
I think I saw this on the Series/Special (discovery channel) "Future Cars". They tried to make it sound like this leap of technology and a super efficient system and hinted or inferred that it was some sort of free energy possibility (my words).

Well the laws of physics i.e. the conservation of energy still holds true, you can't get something for free. It takes energy to compress the air in the first place, and worse yet, compressors are not 100% effcient, nor is the compressed air engine either. So it seems to me that there is a double hit on the effciency loss.

Pete Simmons
06-07-2007, 2:27 PM
"So it seems to me that there is a double hit on the effciency loss."

It is even worse than that! There are many other hands in there grabbing power at every turn. Transmission, Storage conversion and such.

Same holds true for all other fuels.

Everyone thinks electric cars are so energy eff. If it was ever discussed how many watts need to be generated back at some fueled power station to get X(watts) to the wheels we would see why gas at even higher prices is a great deal.

Ken Garlock
06-07-2007, 4:25 PM
I've seen that before and it's a pretty clever concept. The idea of a vehicle running on compressed air isn't new. However, this guy seems to have made it at least somewhat practical.

You can make a car run on almost anything. Unfortunately, it's hard to beat gasoline. Almost nothing has as much energy per drop as gasoline. As gasoline becomes more expensive, perhaps the other fuels will become more practical.

As it stands now, alcohol fuels require twice as much fuel-to-air. Thus, running pure ethanol cuts your mileage literally in half.

Interesting Pat. I thought that the mileage was a function of the energy contained in the actual fuel. Alcohol contains only 80% of the energy that is contained in an equal amount of gasoline, and hence your mileage is only 80% that of gasoline. (Something that the global warming supporters don't mention. But don't get me started on those xxxx.) The fuel to air ratio is the optimal mix of the two to get complete combustion of the fuel. The amount of air used is little more than a mechanical/chemical parameter.

Joe Melton
06-07-2007, 6:19 PM
Well, I guess Exxon and their brethren now need to figure out how to own our atmosphere.
I was an analyst for a study many years ago dealing with the effect of electrical generation capacity if electric cars became efficient enough for regular use in Los Angeles. It was so long ago that I don't recall the particulars, but I do recall a model showing a huge spike in electricity demand about six PM, when people would get home from work. The spike was so severe as to easily overpower current production capacity, and it made the point obvious that some sort of control would have to be placed on when and at what rate the cars could be recharged.
If this car costs $2 to recharge, that is a lot of electricity and a similar study would surely show a shortage of capacity. Also to take into account is the polution created by the generation of the necessary electricity.
There isn't such a thing as free energy, it seems.

Mitchell Andrus
06-07-2007, 6:31 PM
Fancy steam engine.

Pat Germain
06-07-2007, 10:56 PM
Fancy steam engine.

Good point, Mitchell. In fact, I used to visit the Smithsoniam Museum of American History where they have a very large collection of antique steam engines. They routinely run them. How do they run them? They use compressed air.

Pat Germain
06-07-2007, 11:08 PM
Interesting Pat. I thought that the mileage was a function of the energy contained in the actual fuel. Alcohol contains only 80% of the energy that is contained in an equal amount of gasoline, and hence your mileage is only 80% that of gasoline. (Something that the global warming supporters don't mention. But don't get me started on those xxxx.) The fuel to air ratio is the optimal mix of the two to get complete combustion of the fuel. The amount of air used is little more than a mechanical/chemical parameter.

I'm certainly no expert on the molecular composition of alcohol vs. gasoline. However, I do know that what often appear to be simple numbers don't ring true in application. For example, in simple theory, a typical small block V8 can't handle anything more than a 600CFM carburetor. However, if you bolt on a slightly bigger carb, you get more power. Of course, there is an explanation for this, but I don't recall the details.

I used to build hot rods. Possible air/fuel mixtures for a typical piston engine can vary greatly. You can get an engine to run on a very lean mixture (less fuel in the air). However, there are detrimental side effects. Sometimes the engine will start "surging" which is RPMs going up and down at highway speed while the throttle stays in the same position. Also, an especially lean mixture burns very hot. This causes pre-ignition (pinging) which is harmful to engine components. The excessive heat in the combustion chamber can also warp valves. Therefore, preventing such problems requires a richer mixture.

I never built an engine which ran on alcohol. However, I did do some reading about it and every source said the same thing: "To switch from gas to alcohol, the air/fuel mixture requires twice as much fuel". Thus, while alcohol may indeed contain 80% of the energy in gasoline, it may require 100% more fuel to make a typical engine run well.

Wes Bischel
06-08-2007, 12:29 AM
I read a different article that said the storage tanks held the air at over 3400lbs!

Oh, and under the heading "Nothing new under the sun" . . .
http://blog.modernmechanix.com/2006/09/22/compressed-air-motor-runs-car/

Wes

Earl Kelly
06-08-2007, 8:27 AM
I would like to retell a story a friend of mine, who is a race car builder(funny car chassis) and all around mechanical whiz. He's around 65 now and still races his top alcohol funny car from time to time. He's slowing down now, but still does engineering and machine work for Ford Motor co and a Local University working on a Hydrogen motor.

Yrs ago he told me this story must have been 10-20. He went to see a friend and fellow racer over in Mobile AL when they went to lunch he took him for a ride on the interstate in his old pickup truck. When they got up to 60 the guy flipped a valve and put the standard transmission in neutral while taking his foot off the gas allowing the motor to idle. They never slowed down!! His friend explained he had an air motor on the driveshaft and a compressor under the hood, with the motor idleing it provided enough power for the compressor to keep up with the demands of the air motor. A few yrs later he told me the guy moved and he never heard from him again.

Now you can take this in anyway you want. I have no way of validating the story or whether it's even possible. But I thought some might enjoy it and add further to the discussion.

Earl

Cliff Rohrabacher
06-08-2007, 8:35 AM
The thing isn't likely to be very popular.

3400 pounds is a beast of a lot of pressure - in a carbon fiber tank system no less~!! Eventually it'll find it's way out of the tank by means other than where it's supposed to go. Probably the first failure point will be the attachment points for the valve/s. You can only make the epoxy bond just so strong.

The thing will lose energy as the air pressure is dissipated by use.

The thing will have some serious weight limits - but in India everyone is rail thing aren't they?

And of course the infa structure to pump 3400 pounds of air conveniently just isn't there.

They'd be better off with buses.

Ben Grunow
06-08-2007, 4:49 PM
The pressure in those tanks is the same as that of a co2 cylinder for running beer to the taps at the bar and scuba diving tanks etc.. It is not that far off.

Cliff Rohrabacher
06-08-2007, 5:52 PM
The pressure in those tanks is the same as that of a co2 cylinder for running beer to the taps at the bar and scuba diving tanks etc.. It is not that far off.

The Oxygen tanks I've used for welding are maxed about at about 3000 pounds but they are half inch thick steel and the threads for the valves are huge and plenty deep.

I haven't a clue what pressures the CO2 tanks run.

I just think 3400 is a lot for a constant load on a polymer and carbon tank

Ben Grunow
06-10-2007, 9:49 PM
I wouldnt want to sit over those either! (just saying that the pressure is not unheard of)

That car would work for me as my commute is never more than 20 miles round trip. If they only made a 3/4 ton version....